This invention relates to valve actuators, and particularly to a bonnet for opening and closing a quarter turn valve assembly. More particularly, this invention relates to a bonnet configured to operate a quarter turn ball valve assembly and sealed to block escape of fluid from the valve assembly through the bonnet.
Quarter turn valves are commonly used to regulate or throttle the flow of a broad range of fluids in various industrial applications. In some applications, it is necessary to regulate the flow of a noxious liquid, gas, mixture, or other fluid conveyed from one point to another through a pipe or other conduit. A quarter turn valve assembly is mounted in a pipe and operable to regulate the flow of fluid through the pipe. Typically, the quarter turn valve assembly includes a valve housing that is welded to the pipe although it is known to use flanged or threaded joints to connect a quarter turn valve housing to a pipe.
Many different types of quarter turn valves are known. For example, ball valves, butterfly valves, and plug valves, etc. can be configured to function as a quarter turn valve. A quarter turn ball valve assembly includes a valve housing mounted in the pipe and a ball valve mounted in the housing such that it can be rotated "one quarter turn" inside the valve housing to move between its opened and closed position.
A bonnet is an apparatus that is coupled to a quarter turn valve assembly and operated to open and close a quarter turn valve included in the assembly. Typically, the bonnet is connected to a quarter turn valve mounted inside a housing and operable to rotate the quarter turn valve in a clockwise or counterclockwise direction inside the valve housing between a fluid flow-permitting "opened" position and a fluid flow-blocking "closed" position.
Bonnets of the type described above are well known in the art. For example, apparatus including a rack and pinion assembly for operating a rotary valve are disclosed in U.S. Pat. Nos. 4,597,556 to Sandling; 4,976,403 to Bramblet; 3,650,506 to Bruton; 2,983,479 to Thomas; and 1,264,282 to Dearing. Other apparatus for operating rotary valves are disclosed, for example, in U.S. Pat. Nos. 4,867,414 to Hubacek; 4,580,763 to Velan; 4,546,662 to Tremblay; 4,516,754 to Owoc; 4,468,002 to Tremblay; and 4,452,426 to Owoc.
A bonnet configured easily to mount on and detach from most types of quarter turn valve assemblies that are in service in a pipe line and in need of repair would advantageously avoid shortcomings of conventional bonnets. During development of the present invention, it has been observed that many conventional bonnets are designed to connect to only one brand of quarter turn valve assembly. This restriction makes it necessary for service personnel to maintain a supply of many different bonnet styles so that the right bonnet style for each quarter turn valve assembly in service will be available if bonnet repair or replacement becomes necessary. Maintaining a large inventory of different bonnet styles is both costly and troublesome. A single bonnet that is adaptable to mate with and actuate many different brands and styles of quarter turn valve assemblies would be an improvement over conventional bonnets.
It is difficult to retrofit an existing quarter turn valve with a replacement bonnet because conventional bonnets typically cannot be easily removed from the quarter turn valve to permit installation of a replacement bonnet. In some cases, the bonnet is formed to be an integral part of the quarter turn valve assembly and is not easily detached from the quarter turn valve assembly. It will be understood that many quarter turn valves assemblies are welded in place and that it is necessary to use a torch to cut the quarter turn valve assembly out of the pipe line so that a replacement bonnet can be attached to the old quarter turn valve assembly or a new bonnet and quarter turn valve unit can be inserted into the pipe line.
The pipe line can be disabled or otherwise out of service for a long time if it is necessary to cut a quarter turn valve assembly out of the pipe line each time the bonnet needs to be repaired or replaced. Typically, if flammable solvents or fluids are piped through the line, then the entire pipe line system must be shut down in the vicinity of the quarter turn valve assembly and the line must be purged of all fluid prior to commencement of any cutting or welding. In some cases, service personnel must obtain a repair permit to remove an old quarter turn valve assembly and weld a new or reconditioned quarter turn valve assembly and bonnet in place in the line.
It will be appreciated by those skilled in the art that removal and replacement of a quarter turn valve assembly held in place in a pipe line by flanged or threaded connections is still cumbersome and time-consuming. It is still necessary to shut down the line and provide enough skilled service technicians to handle the job.
A bonnet made of modular components that could be quickly and easily removed from a quarter turn valve assembly while leaving the quarter turn valve assembly in place in the pipe line would be an improvement over conventional bonnets. Moreover, a modular bonnet could be disassembled more easily after the bonnet is removed from the quarter turn valve assembly to enhance repair or rehabilitation of the bonnet.
The maximum amount of fluid that can pass through a bonnet from a quarter turn valve assembly to the atmosphere is prescribed by environmental specification, regulation, or law to minimize discharge of noxious fluid through a bonnet to the surroundings. While many conventional bonnets are hermetically sealed to comply with stringent environmental regulations, failure of a single sealed connection within many conventional bonnets could result in unwanted discharge of noxious fluids into the environment. A bonnet formed to include a series of sealed chambers or secondary seals therein to retain or trap noxious fluids in the bonnet should one of the primary sealed connections in the bonnet fail would be an improvement over conventional bonnets.
An improved bonnet is provided by the present invention for operating a quarter turn valve assembly. The quarter turn valve assembly includes a valve housing and a quarter turn valve movable in a fluid-conducting passage to control the flow of fluid through the passage. The valve housing is mounted in a pipe line so that the fluid-conducting passage becomes a part of the pipe line and the quarter turn valve is operable by means of the bonnet to regulate or throttle fluid flow through the pipe line.
According to the present invention, the bonnet includes means for moving the quarter turn valve in the passage formed in the valve housing between a passage-opening and a passage-closing position to regulate fluid flow through a pipe line connected to the passage. The bonnet further includes an actuator housing spaced apart from the valve housing and configured to contain the moving means. The moving means includes a linkage assembly that extends out of the actuator housing and into the spaced-apart valve housing to connect to the quarter turn valve.
A separate adapter block is included in the bonnet and interposed between the actuator housing and the valve housing. The adapter block includes means for supporting the portion of the linkage assembly that extends through the adapter block to reach the valve housing for movement relative to the adapter block.
The quarter turn valve will move in the valve housing to open and close the fluid-conducting passage upon actuation of the moving means in the actuator housing to move the linkage assembly (and the quarter turn valve connected thereto) relative to the adapter block.
Means is also provided for coupling the actuator housing to the valve housing to trap the adapter block therebetween. This causes the actuator housing, adapter block, and valve housing to be held together as a modular unit.
Advantageously, the adapter block can be configured to connect a single actuator housing to a great many styles and shapes of valve housings to reduce inventory of replacement bonnets. This feature enables service personnel to adapt a bonnet to mount on a particular quarter turn valve assembly merely by selecting the proper mating adapter block. It would only be necessary to keep an inventory of inexpensive adapter blocks to permit quick and easy reconfiguration of the improved bonnet of the present invention rather than maintaining a large, diverse stock of conventional bonnets. Further, a modular bonnet can be disassembled quickly and easily to permit efficient repair or rehabilitation of the bonnet including replacement of the various linkages, drive mechanisms, seals, or other components contained in the bonnet.
Moreover, a modular bonnet in accordance with the present invention can be removed from the valve housing containing the quarter turn valve without making it necessary for service personnel to remove the quarter turn valve assembly from its place in the pipe line. Essentially, the quarter turn valve can be moved to close the fluid-conducting passage, the existing bonnet can be removed while the quarter turn valve assembly housing remains attached to the pipe, and a new or rehabilitated bonnet in accordance with the present invention can be mounted on the valve housing.
In preferred embodiments of the present invention, the bonnet can also include a pair of sealing rings mounted on the portion of the linkage assembly that extends through the adapter block. These sealing rings are spaced apart to define a first sealed containment area inside the adapter block to retain and trap therein any fluid that might inadvertently leak from the valve housing into the adapter block. The sealing rings are loaded using a spring force with a predetermined force to extend their useful life as sealing members.
Also, two other sealed containment areas are provided in sequence inside the actuator housing to trap and retain therein any fluid that might inadvertently leak from the adapter block into the actuator housing. The last (or third) of these sealed containment areas is sealed by means of a bellows and at least one O-ring seal. A monitor is coupled to the third sealed containment area and calibrated to indicate if any unwanted fluid inadvertently leaks into the third sealed containment area from the second sealed containment area. Such a leak will only occur in the unlikely event that one or more seals in the first and second sealed containment areas fail.